Honestly I used to buy all that MachIII bullshit.
Now I get the best shave out of these Schick disposable razors.
The bic ones suck, they rip up my face.
The schicks are cheaper than the bics, I think they are like $1.99 at walmart for 10 blades.
I throw them out after 2 uses, so like 10 cents a shave.
The way you make a razor stay sharp is keep it clean, and dry. If you leave it wet, the blade will get corroded, and the little pits will rip up your face, and you think its dull.